1. Field of the Invention
The present invention relates to a liquid droplet jetting apparatus which includes a liquid droplet jetting head which has a jetting port which jets a liquid droplet, and a cap which contactably moves with respect to the liquid droplet jetting head.
2. Description of the Related Art
As a liquid droplet jetting apparatus which includes a liquid droplet jetting head, an image recording apparatus including an ink-jet recording head which jets an ink on to a recording medium has been known. In such image recording apparatus, a maintenance of the recording head has hitherto been carried out for maintaining a jetting condition of the recording head to be favorable by removing forcibly air bubbles and thickened ink in the recording head.
As it has been described in Japanese Patent Application Laid-open No. 2004-58417, in the abovementioned maintenance, generally, a purge suction is carried out in a state in which a cap covers a nozzle formation surface of the recording head, the cap being movable contactably with respect to the nozzle formation surface of the head and being communicated to a pump (suction mechanism). A purge suction is an operation in which a negative pressure is generated inside the cap by the pump, and thickened ink and air bubbles are sucked forcibly from the nozzle, along with the ink. Accordingly, the thickened ink and/or the air bubbles are discharged to a waste-ink tank from a discharge port of the cap.
Moreover, after the purge suction, an idle suction (no-load suction) is also carried out. In other words, the pump is stopped once, and after separating the cap from the nozzle formation surface, the pump is operated again, and remained ink which has remained inside the cap without being completely discharged, is discharged from the discharge port. Accordingly, the ink which has remained inside the cap is prevented from contaminating the surrounding area and/or the ink which has remained inside the cap is prevented from contaminating the nozzle formation surface when the cap has covered the nozzle formation surface.
Generally, a rib, which is projected toward the nozzle formation surface and which is surrounding an area around a nozzle group, is formed in a cap for avoiding a direct contact of the cap with the nozzle. Since this rib is formed of an elastic body (an elastic material) such as rubber, when the cap contacts with the nozzle formation surface, a tip of the rib deforms elastically and makes a close contact with the nozzle formation surface. Therefore, it is possible to seal an interior space of the cap.
As shown in FIG. 10A, when a cap 551 is driven by an elevating mechanism (ascending and descending mechanism) which is not shown in the diagram, and has made a close contact with a nozzle formation surface 504a of a recording head 504, a space 601 is formed between the cap 551 and the nozzle formation surface 504a. Consequently, at the time of sucking the ink from the nozzle by a pump 656 which communicates with a discharge port 553 of the cap 551 at the time of the purge suction, the suction of the ink inside the nozzle starts after discharging the air in the space 601 firstly. Therefore, when a volume of the space 601 is large, it takes time till starting the suction from the nozzle, and there is a problem that it is not possible discharge efficiently the ink from the recording head 504 at the time of the purge suction.
Whereas, in FIG. 10B, an ink absorber 655 in the form of a sponge having a constant hole ratio all over is arranged at an interior of the cap 551. Accordingly, it is possible to absorb the ink by the ink absorber 655, and to reduce practically the space 601 which is formed between the cap 551 and the nozzle formation surface 504a. As a result, a suction efficiency of the purge suction is improved.